1. Field of the Invention
This invention relates to the manufacture of integrated circuit devices, and in particular, to matrix lead frame configurations designed to facilitate the assembly of integrated circuit devices.
2. Related Art
The advent of surface mount technology has given rise to a proliferation of new sizes and shapes for integrated circuit devices. These new device styles include Small Outline IC's (SOIC's), Plastic Leaded Chip Carriers (PLCC's), and Small Outline J-leaded devices (SOJ's), all well known to those skilled in the art. In addition, integrated circuit devices in the familiar DIP package style come in a large variety of sizes and shapes.
Most integrated circuit devices are assembled around a lead frame. These lead frames come in a large variety of sizes and shapes. Typically, the lead frames themselves are manufactured in long strips of many individual units. These long strips are wide enough to accommodate from one to approximately three or four lead frames. When a strip of lead frames is more than one lead frame wide, the strip is referred to as a matrix. In the present invention, a lead frame matrix refers to a strip of lead frames which includes one or more lead frames along its width.
The state of the prior art is such that each matrix of a given size and shape lead frame has its own unique width determined by the width of an individual lead frame and the number of lead frames making up the width of the matrix. Thus, the state of the prior art is such that there is great variety in the widths of matrices.
Typically, final assembly of an integrated circuit device requires that a semiconductor chip be affixed to the bar pad of a lead frame and that the leads of the lead frame be electrically connected to the integrated circuit on the upper surface of the semiconductor chip. Subsequently, the leadframe and affixed semiconductor chip are packaged in a material such as plastic. One of the last assembly steps is "trim and form" in which any excess leadframe material is trimmed away and the leads protruding from the packaging material are bent to their final form.
Often, the machinery for carrying out the final assembly includes means well known in the art for handling a matrix of lead frames. Because of the diversity of matrix widths, the prior art matrix handling means are adjustable to a number of different widths. Integrated circuit assembly machinery is very expensive, so the same machinery is made adaptable to assemble a variety of different types of Integrated circuit devices, each type having its own characteristic size and shape.
Unfortunately, the matrix handling means usually require a down time of from four to eight hours to change over so that they can handle a different width lead frame matrix. Associated with this amount of down time is a yield loss for the next twenty-four hours of approximately five to ten percent.